Gas regulator for a firearm



May 14', 1957 E. M. HARVEY 2,791,944

GAS REGULATOR FOR A FIREARM Fild April "I. 1954 2 Sheets-Sheet 1 IN VENTOR.

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GAS REGULATOR FOR A FIREARM Filed A ril '7, 1954 2 Sheets-Sheet 2QTTOEIYE- Y5 GAS REGULATOR .FOR A FIREARM Ear e M. Harvey, Agawam, Mass,assignor to the United States of America as represented by the Secretaryof the Army Application April 7, 1954, Serial No. 421,717 4 Claims. (Cl.89-493) (Granted under Title35 U. S. Code (1952), see. 266) Theinvention described herein may be manufactured and used by or for theGovernment forgovernmental'purposes without the payment of 'any royaltythereon.

This invention relates to gas-operated firearms and more particularly toimprovements in the gas systems thereof.

it is an object of this invention to provide for tirearms, a gas systemwherein the parts are easily disassembled and assembled.

It is anoti er object of this invention to provide for gas-operatedfirearms a gas regulator device which may be removed and replacedwithout changing the predetermined adjustment setting thereof.

it is a further object of this invention to provide for a firearm gassystem, a separately replaceable gas cylinder which is locked inposition 'by thegas regulator device.

it is a still further object o'fthisinverrtion to provide for automaticfirearms a gas system wherein the piston is provided with a longer powerstroke in terms of time and distance and a lower maximum velocity.

it is the specific object of this invention to provide for firearmsystems an easily adjusted gas regulator device wherein the adjustmentorifice and valve remain relatively frec of harmful carbon and/ ormetallic deposits.

The specific object of the invention "as Welles other objects andadvantages will clearly appear from a description of the preferredembodiment as shown in the accompanying drawings in which:

Fig. 1 is a fragmentary partially cross-sectional side view of the gassystem of a'firearm;

Fig. 2 is an enlarged perspective view of the gas regulator valveassembly; and

Fig. 3 is a perspective. exploded view of the gassystem.

Shown in the figures is a firearm barrel 12 having a cylindrical bearingportion 13 with a radial gas port 14 and a transverse chorda'l channel15 provided therein. Mounted to barrel 1-2 is a-bracket '16 having acylindrical sleeve portion 17 arranged to snugly encircle bearingportion 13. A tapered pin 18 is mounted transversely through sleeve 17to be received by channel '15 for fixedly securing bracket 16 to barrel12. Integral with the top portion of sleeve 17 is a body 19,including--asubstantially rectangular housing 2! which extends beyond the front endof sleeve 17 to 'form a forwardly projecting portion 21. Providedthrough body 19 is a longitudinal hole 22 which forms a semicylindricalchannel 23 in the underside of projecting portion 21. A radialpassageway 24 of slightly larger diameter than .gas port 114 is arrangedthrough the underside of housing 24) for alignment with such gas port.lrovided radially through the top portion of housing 2%, diametricallyopposite passageway 24, is a cylindrical aperturefi l WhiChiiS Of largerdiameter than such passageway. Aperture '25 is counterbored and threadedfrom the top side of housing 20, as noted at 39, to form an annularshoulder 26.

Slidably and rotatably received by hole 22 is a gas cylinder member 27having a smaller outside diameter ftatcs Patent portion 28 receivable bysuch hole and a larger outside diameter portion 29 which extendslongitudinally forward 1 from an annular step portion 30. Projectingfrom the circumference of smaller diameter portion 28 is a semiannularlug 31 which is arranged to be rotatably received in a mating groove 32,provided in semicylindrical portion 23, when step 36 is in engagementwith the front side of housing 20, whereby gas cylinder 27 is securedagainst linear displacement.

Gas cylinder 27 is provided with a longitudinal bore 33 which iscounterbored at both ends to form a rear cylinder portion 34, whichcooperates with a piston 35, and a front reservoir chamber 36. The frontend of chamber 36 is sealed by a threaded closure member 37. A radialgas port 38 of slightly larger diameter than passageway 24 is arrangedthrough gas cylinder 27 to provide communication between such passagewayand bore 33. The junction of gas port 38 with bore 33 forms an orifice4t). Diametrically opposite gas port 33 is a cylindrical hole 41 whichis of similar diameter as aperture 25 and is coaxial therewith.

A hexagonal headed bushing 42 is arranged to be threadably received bycounterbore 39 and to bottom against shoulder 26, thus, sealing thegases from the threadedportion. Bushing 42 is held in place by a nut 43thread-ably engaged therewith which is tightened against housingExtending axially through bushing 42 is a threaded bore 44 which isarranged to threadably receive in clockwise rotation a regulator screw45. Regulator screw 45 is comprised of a head portion d6, suitablyslotted for turning, a threaded portion 47 cooperable with bore 44, arod portion 4% of smaller diameter than such threaded portion and anannular ledge portion 53 formed by the junction of such threaded and rodportions. Rod portion 48 is arranged to be snugly received by hole 41and aperture 25, whereby gas cylinder 27 is secured against displacementto bracket 16, and is terminated by a conical portion 49. Conicalportion 49 is arranged to be axially received by gas port 38, which isof smaller diameter, for cooperation with orifice it? to regulate thepassage of gases from barrel 12 to bore 33 of gas cylinder 27.

A check nut 52 is threadably engaged to threaded portion 47 for securingregulator screw &5 against rotation after being adjusted. Provided ineach face of the hexagonal head of bushing 42 is an inscribed numericalreference 50, which progress seriaiiy from 1-6 in counterclockwisedirection, and alignable therewith is an index mark 51 on thecircumference of head id of regulator screw 45.

In operation, the gases from an exploded cartridge enter gas port 14after the projectile has passed thereby and pass through passageway 24and gas port 38 to be metered at orifice 44 by conical portion 4) ofregulator screw 45. The metered gases enter bore 33 of gas cylinder 27and proceed to fill such bore and reservoir chamber 36. When thepressure of the gases in chamber 36 and bore 33 is sufficient, piston 35is actuated thereby to a recoil position. It is obvious that with thecomparatively large reservoir provided by bore 33 and chamber 36, anaccelerated pressure is applied to piston 35 rather than aninstantaneous impact as in most conventional gas systems. Further, afterthe cartridge projectile has left the muzzle of barrel 12, whereby thegas commences its power stroke before the gases in chamber 3 36 arebrought to maximum pressure and continues during the pressurizing of thechamber and after the projectile has left the bore of barrel 12. Thus,the power stroke of piston 35 is increased in terms of time and distanceand has a lower maximum velocity than those in conventional gas systems.

Moreover, as bore 33 and chamber 36 receive a comparatively large volumeof gases the velocity of the gases passing over conical portion 49 andthe associated gas ports into gas cylinder 27 blow the debris of carbonand/or metallic deposits therefrom. Also, as the locations of theadjustment portions of the gas system are relatively close to the boreof barrel 12, the heat of the gases are cooled very 'little as they passthereby. Consequently, nearly all of the contamination present in thegases remain in a gaseous state until after passing orifice 4-0.

If at any time it is necessary to remove gas cylinder 27, nut 43 isunloosened to free bushing 42 which may then be removed from counterbore39 with regulator screw 45 being withdrawn from aperture and hole 41.Gas cylinder 27 may then be rotated to free lug 31 from groove 32 andwithdrawn forwardly from bracket 16. Because regulator screw 45 need notbe disturbed from its adjustment relationship with bushing 42 duringdisassembly of gas cylinder 27. as best shown in Fig. 2, when bushing 42is reinstalled in counterbore 39 and bottomed against shoulder 26 thegas system is in the same adjustment as before disassembly, thus savingconsiderable time. In event regulator screw 45 is disassembled frombushing 42, the relationship of index mark 51 with the associatedinscribed numerals St is a reminder to the operator of the setting towhich the regulator screw should be repositioned at assembly.

From the foregoing, it is very apparent that there is here provided afirearm gas system in which the regulating means are kept free offoreign deposits and which is provided with a long power stroke, interms of time and distance and a low maximum velocity and is easilyadjusted, assembled and disassembled.

Although a particular embodiment of the invention has been described indetail herein, it is evident that many variations may be devised withinthe spirit and scope thereof and the following claims are intended toinclude such variations.

I claim:

1. A gas system for a firearm having a barrel with a bore, said gassystem including a gas cylinder member having an axial bore counterboredat one end to form a reservoir chamber and at the opposite end to form acylinder arranged for cooperation with a piston, said gas cylinder beingreplaceably mounted to the barrel by means of a cylindrical bracket, apassageway between the bore of the barrel and said cylinder and throughsaid bracket, said passageway forming an orifice at the junction thereofwith said axial bore, and a regulatable valve means cooperable with saidbracket and said gas cylinder for securing said gas cylinder to saidbracket, said valve means being provided with a conical portionextending axially into said passageway for adjustable cooperation withsaid orifice whereby the high velocity of hot gases passing between saidpassageway and said conical portion from the bore of the barrel keepsforeign deposits free from said conical portion and said orifice.

2. In a firearm having a barrel with a bore, a bracket securely mountedto the barrel, said bracket being provided with a longitudinal borearranged to slidably receive a hollow gas cylinder member, said gascylinder member being provided with a front counterbore portion forminga reservoir chamber and a rear counterbore portion forming a cylindercooperable with a piston, passage means providing communication betweenthe bore 4 of the barrel and the interior of said gas cylinder member, agas regulator device comprised of a bushing threadably mounted in saidbracket to bottom against an annular shoulder therein, a regulator screwthreadably mounted through said bushing, means for locking said bushingto said bracket and lock means for securing said regulator screw againstrotation to said bushing, said bushing being provided with a series ofreference marks around the perimeter thereof, said regulator screw beingprovided with a head portion suitably adapted for turning and an indexmark alignable with said reference marks and a rod portion terminated bya conical portion, said rod portion being snugly mounted for rotationthrough said bracket and said gas cylinder member whereby said gascylinder is secured against displacement to said bracket, said conicalportion extending axially into said passageway to regulate the gasespassing from the barrel to the interior of the gas cylinder member andwhereby said conical portion and said passageway are kept free offoreign deposits from the gases, and whereby said regulator device isreinstallable after removal from said 'bracket with the adjustmentsimilar to that determined before removal.

3. In a firearm having a barrel with a radial gas port for passage ofgases therefrom, a bracket fixedly mounted to the barrel and providedwith a bore disposed longitudinally to the barrel and a passagewayextending from said bore to the gas port, a cylindrical apertureextending (from said bore through said bracket diametrically oppositesaid passageway, a shoulder formed by a counterbore portion introducedfrom the outer end of said aperture, a gas cylinder slidingly receivedby said bore, an

operating piston mounted for sliding movement in said gas cylinder,cylindrical port means extending from said passageway to the interior ofsaid gas cylinder forwardly of the travel of said piston, a cylindricalopening through said gas cylinder diametrically opposite said portmeans, a bushing threadingly received by said counterbore portion tobottom against said shoulder, a regulator screw threadingly mountedthrough said bushing and provided with a rod portion received by saidopening and said apertwo to cooperate therewith for securing said gascylinder to said bracket, and a conical portion terminating said rodportion, said conical portion being cooperable with said port means forregulating the passage of gases from the barrel to said gas cylinder.

4. In a firearm having a barrel, a bracket fixedly mounted to the barreland having a bore therethrough, a gas cylinder mounted through saidbore, and a cylindrical valve member mounted transversely to saidcylinder through mating holes in said cylinder and said bracket forcooperation with a passageway between said gas cylinder and the barreland directly opposite said holes to regulate the passage of gases tosaid cylinder from the barrel and for restraining said cylinder againstrotational and longitudinal movements in said bore.

References Cited in the file of this patent UNITED STATES PATENTS454,403 Odkolek June 16, 189l 709,883 Knight Sept. 30, 1902 2,144,241Eiane Jan. 17, 1939 2,149,512 Eiane Mar. 7, 1939 FOREIGN PATENTS 19,096Great Britain of 1903 OTHER REFERENCES War Department Manual No. 1926,March 1912, Handbook of the Benet-Mercie Machine Rifle, Plate IV.

